The present invention relates to alarm clocks which awaken one person without disturbing others sleepers in the same bed or same room.
Alarm clocks have an ancient history, the philosopher Plato (428-348 BC) was said to possess a water clock which would wake him for his early lectures. The Buddhist monk Yi Xing (683-727 AD) devised a striking clock. In 1238 AD a water-powered alarm clock that announced the appointed hours of prayer was completed in 1235. User settable mechanical alarm clocks date back to at least the 15th century in Europe.
The need for alarm clocks in modern times is particularly driven by current lifestyles where almost everyone is required to attend work, classes or appointments at set times. Although it is perhaps beneficial in setting the body's circadian rhythms to awake naturally to the rising sun this is not an option for the vast majority of people who sleep in a closed environment with the windows shut and the shades drawn, and for whom waking times cannot vary with the seasons. The alarm clock, then, is a sometimes painful necessity of life. If two people are sleeping in the same bed or the same room there is the additional problem of the person for whom the alarm is not intended being waken by the alarm clock. For the second person, who often does not have the same schedule, the result is interrupted sleep with its attendant loss of sleep quality, or even the loss of the ability to return to sleep and the cutting short of the second person's natural requirement for sleep of a certain number of hours which varies between people both in the number of hours and the particular schedule they may keep.
Vibrating alarm clocks have been developed that at least in theory have the ability to wake one person without disturbing others in the same bed or room. Such vibrating alarm clocks may be placed under or in one sleeper's pillow or strapped to the arm. Nevertheless the vibrating alarm clock can produce sufficient sound to wake others if they are light sleepers and requires wearing an awkward wrist alarm, or placement of a vibrating alarm in or under a pillow in which case the vibration may not be sufficient to be reliable without producing a level of stimulus which will wake other sleeping companions, or will itself be unpleasant to the one awoken.
In recent times, taking advantage of advances in electronics, alarm clocks have been developed to awake a person at a particular stage in sleep by using sensor technology such as EEG electrodes or accelerometers calculated to avoid sleep inertia or grogginess following an abrupt awakening. Another approach to mediating grogginess is to employ a dawn simulator where a bedside lamp, or a light on the alarm clock itself is slowly increased in brightness over a set period of time which also is thought to be helpful in preventing seasonal affective disorder (SAD). These technologies do not directly address the problem of undesirable waking of roommates in the same room or a spouse sleeping in the same bed.
What is needed is an alarm clock which can combine light and sound stimulus that wakes only one person without disturbing others who are sleeping nearby.